It is different for everyone depending on combinations of age, circumstances, personalities, support available and many other factors.
Covid took my mum in traumatic circumstances, it financially screwed us as dh barely worked for almost 2 years and we had no government support, it fell over 2 school exams years for my teen ds when the little online learning he got was very poor quality. It was hard.
Now, I still miss my mum every day, financially we are surviving/slowly recovering.
For ds covid had some huge positives such as having to be more independent, taking responsibility for his school work and having less distractions during studying let him know what he was capable of if he works hard and it played a part in focusing him to get into his uni and course of choice. The peak teen "drinking in parks" years passed him by and by the time he came out of covid he was too old for it (I'm glad we missed them!). He kept his social connections alive with online games, long outdoor walks, or challenging each other with keep fit targets and sharing photos of meals they learned to cook. I said to him towards the end of pandemic years, he went into it a boy and came out a young man and I am proud of what he achieved during it.
If covid could appear to have such a positive impact on my teen ds, it stands to reason it could also appear to have significant negative impacts on others of the same age. Speaking to other mums I know, their dcs experiences vary greatly, those that had some issues with school and social interaction prior to covid, and/or needed more support from either schools or parents (who were not able give it for whatever reasons such as both parents being key workers and no other family support) seem to have been hit the hardest.
With the teens years already being very unpredictable and "normal" life known to throw in its own curve balls, I guess most of us will never know, individually, if our dc will have had significantly different long term outcomes if they hadn't lived through covid. Looking at what is happening around the world now, while it was hard and is still hard, there is much worse they could have gone through.